Gravity, friction, velocity of rotation, and load forces applied during operation to bearings, drive shafts, driven shafts, rotors, and other components of driving and driven machines (collectively, "machine members") contribute to wear, fatigue and degradation of machine members. High speed circular rotation of shafts mounted in bearings gives rise to centripetal force, a force which is reacted to by centrifugal reaction. Angular velocity and angular acceleration of machine members subjected not only to high velocity but significant loads may also induce gyroscopic effects on machine members turning or rotating rapidly. Machine members also may be subjected to significant loads about the geometric and rotational axes of a machine member. As is commonly known, when two forces act on a shaft, pin, axle or similar rod or assembly (collectively, "shaft"), a torque is formed whose vector along an x-axis may produce a rotation about the y-axis known as precession. Such rotation may generate significant angular velocities. The gyroscopic effect and the torque may individually and collectively contribute to inducing rapid wear of shafts and bearings in which shafts are mounted. In any rotating or reciprocating machine in which angular accelerations and velocities are present, unbalanced forces may lead to high stresses and vibrations. Further, if the speed of a shaft or rotor is slowly increased from rest, a speed may be achieved at which a deflection increases suddenly, a phenomenon known as "whirling." A shaft which is balanced will rotate around the center of gravity or axis of rotation of a shaft. However, if the shaft rotates at an angular velocity, the shaft may deflect a distance from the center of gravity or axis of rotation due to centripetal reaction. Rotation also may induce undamped free vibrations. All of these forces and phenomena, and others, may contribute to rapid and excessive wear among machine members, particularly in machine members subjected to high loads and forces. This is particularly true, but not exclusively, in machine members associated with impact crushers. Excessive and rapid degradation and wear of machine members in crushers may cause significant down time, expensive delays in repair and replacement of machine members, and delays in use of the crushers while one or more worn machine member is identified, inspected, removed and replaced. Frequent replacement of machine members causes significant expense to the operator. Such delays, costs and expenses are compounded if the apparatus, such as an impact crusher, is located at a remote site.
For example, a wide variety of impact crushers are used in commerce to reduce the size of large earth materials to smaller sized and shaped aggregate. The construction industry trades employ a variety of impact crushers to reduce large aggregate to aggregate sizes and shapes required to satisfy construction specification for mixtures and admixtures of aggregate with cement and other ingredients, and for further processing of size reductions, chemical leaching, and other stages of use. Construction industry use of impact crushers is but one example of the need to reduce wear on machine members.
Generally, impact rock crushers provide a component for introducing aggregate into a device or devices for crushing the aggregate. Most impact crushers are designed to rely on centrifugal force to disperse large aggregate through the crusher, and to impact the larger aggregate against a variety of impact crusher components to break up, reduce in size, and ultimately eject from the crusher an aggregate composed of desired shapes, sizes and consistencies. Intense efforts have been made to achieve improvements in the design and construction of components of impact crushers to reduce the cost of acquiring and operating crushers, to enhance wear resistance of the component parts of crushers, and to facilitate rapid replacement of worn parts of crushers to enable the user of crushers to lose the least possible amount of time during which a crusher is inoperative due to worn parts.
Such improvements are exemplified by those shown in U.S. Pat. No. 3,955,767 issued May 11, 1976 to Mason R. Hise, and U.S. Pat. No. 4,690,341 issued Sep. 1, 1987 to Mason R. Hise and Neil R. Hise, the latter being the inventor of the present invention (collectively, the "Hise Patents"). The Hise patents are instructive on the number and variety of components which may be included in an impact crusher and consequently exposed to wear during operation of an impact crusher. Due to significant loads and stresses placed on many components of impact crushers during operation, friction, fracture, impact, pulsation, angular velocity, and angular acceleration of rotating shafts, may cause driven shafts and bearings to wear rapidly. An impeller of an impact crusher is known to rotate at speeds from about 500 to about 2000 revolutions per minute. The rotation of an impeller, in combination with centrifugal force, creates a material flow of aggregate.
As a result of persistent use of an impact crusher, and the high forces applied to machine members during operation of an impact crusher, replacement of machine members causes down time to repair, refit, and replace machine members. Additional expenses are associated with replacing worn machine member, inventorying replacement components, and delivering a replacement machine members to what is often a remote site, to say little of the general frustration associated with having to stop the aggregate crushing process to replace worn machine members.
What is needed, therefore, is an apparatus for increasing the wear life of machine members during operation of a machine. Particularly what is needed is an apparatus for reducing wear of shafts and bearings associated with impact crushers.
In light of the above, it is an object of the present invention to provide an apparatus for increasing the wear life of machine members, particularly machine members exposed to considerable rotational and vibrational loads and forces.
Another object of the present invention is to provide an apparatus for increasing the wear life of machine members, particularly those members of a machine comprising bearings in which a driven shaft rotates, including a shaft which rotates in a bearing at high velocities and accelerations.
Yet another object of the present invention is to provide an apparatus for increasing the wear life of machine members, including bearings in machines requiring one or more of the bearings to be adjusted loosely in relation to the shaft or shaft assembly, rather than tightly on the driven or rotating shaft of the machine, thus increasing unbalanced radial loads on the bearing or bearings.
Still another object of the present invention is to provide an apparatus for increasing wear life of machine members by reducing or dampening excessive vibrations in an apparatus in which two or more driving machines may be used to rotate a shaft or shaft assembly, thus increasing unbalanced harmonics in the machine members of a driven shaft or shaft assembly.
Still another object of the present invention is to provide an apparatus for increasing the wear life of machine members while also permitting the user to increase the rotational speed of a driven shaft, and apply greater loads to the machine.
Another object of the present invention is to provide an apparatus for increasing the wear life of machine members by relieving pressures and forces on both driven shafts and bearings supporting the driven shafts.
Yet another object of the present invention is to provide an apparatus for increasing wear life of machine members, and a process for manufacturing an apparatus for increasing the wear life of machine members, which respectively are easy to use and to practice, and which are cost effective for their intended purposes.
These and other objects, features, and advantages of such an apparatus for increasing the wear life of machine members will become apparent to those skilled in the art when read in conjunction with the accompanying following detailed description, drawing figures, and appended claims.